Infrared detection systems are known for sensing infrared radiation from a radiating object or source and for providing an indication of sensed temperature or a display of temperature profile. Many infrared detection instruments are in the nature of non-contacting thermometers for providing measurement of radiation from a single localized area at which the instrument is aimed. Such instruments generally employ an infrared detecting element which provides an electrical signal in response to received radiation and which signal is processed by associated electronic circuitry to provide an output indication of sensed temperature. Systems are also known in which electronic or mechanical scanners are employed to produce a two-dimensional display of sensed radiation and which display is provided typically on a cathode ray tube screen or on a pen recorder. These systems also require active electronic circuitry and an active sensing instrumentality such as an image tube or a sensor element and associated scanner. As a consequence, such known systems are relatively expensive and complex.
Liquid crystal materials are also known for providing a visual representation of temperature in the form of colors which correspond to sensed temperatures. In general, such liquid crystal materials are applied either in film form or as a coating to a radiating surface for direct sensing of surface temperature and to exhibit by virtue of color changes the surface temperature profile.